The Asano family was among the strong supporters of Toyotomi Hideyoshi and the head of the family had a post as one of the Five bugyo (Five magistrates). But in the decisive Sekigahara battle, the army of the Asano family joined the eastern forces lead by the Tokugawa family. In 1615 the Asano family also fought on the side of Tokugawa, and in 1616 the Asano lord married the third daughter of Tokugawa Ieyasu and thus received an important position in the politics at the Edo period.
In 1619, with the result of a punishment of Fukushima Masanori, Asano Nagaakira moved to Hiroshima and became the lord of Geishu domain. From that time the Asano family held this position until the Meiji Restoration. That was the rare case because usually lords often changed their lands, as had Fukushima Masanori.

The Asano family had several lords who were known by their activities at the national level. One of them was Asano Shigeakira 【1743～1813】who managed to improve domain’s finances by stimulation of national products. Geishu domain was one of the main suppliers of rice to the national market. Also, Hiroshima was known for production of paper, Japanese persimmon, and iron. Asano Shigeakira was well-known at the national scale for his promotion of Confucianism, and his nephew married the daughter of the 8th shogun Ienari.
Also well-known was the last lord Asano Nagamichi 【1812～1872】, who was the lord at the time of Restoration of the imperial rule (大政奉還) and civil war（戊辰戦争） that ended the rule of samurai in Japan.　In 1872, in Japan, domains (including Geishu han) were abolished and prefectures (廃藩置県) were created as the main administrative units from Meiji until now. Most of the property rights held by domain lords, including ownership of castles, was placed under Meiji state supervision.

Now Hiroshima Castle is one of the most popular tourists spots in Hiroshima. It is reduced to the size of the inner moat, the honmaru and the ninomaru (the main and second compounds). It was protected from invaders by three concentric moats: the outer moat, the middle moat, and the inner moat.
In the Edo period Hiroshima Castle stretched a full kilometer north-south and east-west. It covered 900,000 square meters or nearly 90 hectares, which that is more than 25 times the size of Hiroshima baseball stadium. The modern soccer stadium covers only a small part of the area of the old castle of the Edo period.
The castle tower was located at the honmaru (main compound) in the center of the castle where the residence of the daimyo was also built. But the central tower was mainly the defensive construction designed to be the last stronghold in the event of a battle. It also symbolized the power of the lord. However, while in Hiroshima, the lord spent his time in the palace called Honmaru-Goten. Most parts of the administrative buildings of the Geishu han were located in the Sannomaru (the third compound) and the other areas around the Honmaru as well as the residences of the high-ranking samurai.

In the Meiji period, Hiroshima castle became state property and was supervised by army authorities. Gradually most of it’s parts were dismantled. Firstly, destroyed was by fire the palace of the lord (Honmaru-Goten); next were the outer walls and Ninomaru and Sannomaru. The moats were filled in and replaced by roads existing even now. In the place of castle facilities were built the soldiers’ barracks, the 5th Division headquarters and the Shrine “Gokoku jinja”.
The military authorities dismantled most parts of castle, and at the time of the atomic bombing, existed only part of the stone base (ishigaki) and Central tower that, also was used for the Japanese army and was destroyed by the atomic bomb with the other army training and education facilities.

After the Meiji Restoration, the castle came to serve as a military facility. In 1877, the Western-style two-stored building of the Hiroshima Chindai Headquarters (later the Imperial General Headquarters) was built of wood. The Imperial General Headquarters was based there during the First Sino-Japanese War (1894-1895 - Meiji 27-28). During the final months of World War II, the castle served as the headquarters of the 2nd General Army and 5th Division was stationed there to defend from the expected invasion of the Japanese mainland.

Hiroshima grew rapidly because of new technologies. One of the examples is the castle site. At time of the Sino-Japanese War, the main military headquarters was located in Hiroshima City and the need for water supply increased. Therefore, it was decided to construct a modern water supply system, which was designed by the British engineer W.K. Barton.
Sakura pond was built in 1898 to commemorate the construction of a water supply in Hiroshima which was one of the first in the country.  Initially, the pond did not have a name, but in 1925 it was named "Cherry Blossom Pond".

Also, for a long time Hiroshima served as the most western station of the Japanese railroad lines. This railroad was a key reason to choose Hiroshima to be the Imperial Military Headquarters during the First Sino-Japanese War.
A two-story wooden Western-style building built in 1877 was destroyed by the atomic bomb. Today only the stones of the foundation remain.

Near there are the ruins of the Western-style building where Empress Shoken, the wife of Emperor Meiji, stayed during the Sino-Japanese War. Originally it was a two-story wooden Western-style building built in 1890 as the government building for the 5th Division Supervision Department. It was destroyed by the atomic bomb, and now one can see only the stones of the foundation.

Near Gokoku jinja shrine you can see the air defense operation room of the Chugoku Military District Headquarters that was established at the end of the Pacific War. Near the entrance of this operation room site, there is a memorial monument for the Chugoku Military District Headquarters and the mobilized students. About 90 students from “Hijiyama joshi koto gakko” assisted military personal in the operations room. They worked in three shifts of 30 students.

It is rumored, that it was the girl student who made the first call from the room to Fukuyama headquarters that in Hiroshima was used a bomb of a powerful new type.
Many well-known persons have visited Hiroshima, but only some of them care to look at the castle. One of them was the Cuban revolution leader Che Guevara who visited it in 1959. The actual purpose of his visit is unknown, but it is clear that he was stimulated by an interest in the atomic bombing incident.